Ultrasonic bone assessment apparatus and method

Abstract

An invention is disclosed for locating a region of interest in the calcaneus. A pair of ultrasound transducers are positioned on the medial and lateral sides of the heel, respectively. The positioning is based on a size of a portion of the body of a subject upon whom the ultrasound assessment of the calcaneus is to be made. In a presently preferred embodiment, the length of the foot from the back to the head of the first metatarsal is used in conjunction with a proportionality constant and an angle, to position the pair of transducers. The positioning so obtained facilitates (i) reproducible measurements and (ii) comparisons of the results obtained in one person with another, because relatively analogous portions of the highly heterogeneous calcanei are assessed in both. In an alternative embodiment, a single transducer is positioned similarly on the heel, operating in pulse-echo mode.

1. A method for positioning a pair of ultrasound transducers at a region of interest of a calcaneus within a foot of a subject, comprising the following steps:
 a. Placing said subject's foot in a fixture between said pair of ultrasound transducers such that said pair of ultrasound transducers are disposed on medial and lateral sides, respectively of a heel of said foot, said fixture containing a first surface upon which a bottom of said foot rests, and a second surface upon which a back of said foot rests; 
 b. Selecting a proportionality constant, an angle, and a reference frame; 
 c. Identifying a size associated with said subject's foot; and 
 d. moving said pair of ultrasound transducers to a location that is a distance equal to said proportionality constant times said size at said angle with respect to said reference frame; 
 to thereby locate said region of interest of said subject's calcaneus; 
 wherein said moving step includes the substep of adjusting a position of a marker corresponding to said size by a second distance, adjustment of said marker causing movement of said pair of ultrasound transducers. 
 
     
     
       2. The method according to  claim 1 , wherein said size is a length from said back of said foot to a head of a first metatarsal of said foot. 
     
     
       3. The method of  claim 1  wherein said reference frame has an origin at an intersection of said first and second surfaces and said location is at said angle relative to said first surface. 
     
     
       4. The method of  claim 1  wherein said distance and said second distance are related by said proportionality constant. 
     
     
       5. A method for positioning a pair of ultrasound transducers at a region of interest of a calcaneus within a foot of a subject, comprising the following steps:
 a. Placing said subject's foot in a fixture between said pair of ultrasound transducers such that said pair of ultrasound transducers are disposed on medial and lateral sides, respectively of a heel of said foot, said fixture containing a first surface upon which a bottom of said foot rests, and a second surface upon which a back of said foot rests; 
 b. Selecting relationships between x and y motions of said pair of ultrasound transducers, respectively, and a reference frame, and identifying at least one size associated with said foot of said subject; 
 c. moving said pair of ultrasound transducers in accordance with said relationships to thereby locate said region of interest of said subject's calcaneus; 
 wherein said moving step includes the substep of adjusting a position of a marker corresponding to said size by a distance, adjustment of said marker causing movement of said pair of ultrasound transducers. 
 
     
     
       6. The method according to  claim 5 , wherein said at least one size includes a length from said back of said foot to a head of a first metatarsal of said foot. 
     
     
       7. A method for positioning a pair of ultrasound transducers at a region of interest of a calcaneus within a foot of a subject, comprising the following steps:
 a. Placing said subject's foot in a fixture between said pair of ultrasound transducers such that said pair of ultrasound transducers are disposed on medial and lateral sides, respectively of a heel of said foot, said fixture containing a surface upon which a bottom of said foot rests; 
 b. Selecting relationships between x and y motions of said pair of ultrasound transducers, respectively, and a reference frame, and identifying at least one size associated with said foot of said subject; 
 c. moving said pair of ultrasound transducers in accordance with said relationships to thereby locate said region of interest of said subject's calcaneus; 
 wherein said moving step includes the substep of adjusting a position of a marker corresponding to said size by a distance, adjustment of said marker causing movement of said pair of ultrasound transducers. 
 
     
     
       8. The method according to  claim 7 , wherein said at least one size includes a length from a back of said foot to a head of a first metatarsal of said foot. 
     
     
       9. A method for positioning an ultrasound transducer at a region of interest of a calcaneus within a foot of a subject, comprising the following steps:
 a. Placing said subject's foot in a fixture such that said ultrasound transducer is disposed on a side of a heel of said foot, said fixture containing a first surface upon which a bottom of said foot rests, and a second surface upon which a back of said foot rests; 
 b. Selecting a proportionality constant, an angle, and a reference frame; 
 c. Identifying a size associated with said subject's foot; 
 d. moving said ultrasound transducer to a location that is a distance equal to said proportionality constant times said size at said angle with respect to said reference frame; 
 to thereby locate said region of interest of said subject's calcaneus; 
 wherein said moving step includes the substep of adjusting a position of a marker corresponding to said size by a second distance, adjustment of said marker causing movement of said ultrasound transducer. 
 
     
     
       10. The method according to  claim 9 , wherein said size is a length from said back of said foot to a head of a first metatarsal of said foot. 
     
     
       11. The method of  claim 9 , wherein said side of a heel is a medial side. 
     
     
       12. The method of  claim 9 , wherein said side of a heel is a lateral side. 
     
     
       13. A method for positioning an ultrasound transducer at a region of interest of a calcaneus within a foot of a subject, comprising the following steps:
 a. Placing said subject's foot in a fixture such that said ultrasound transducer is disposed on a side of a heel of said foot, said fixture containing a first surface upon which a bottom of said foot rests, and a second surface upon which a back of said foot rests; 
 b. Selecting relationships between x and y motions of said ultrasound transducer, and a reference frame, and identifying at least one size associated with said foot of said subject; 
 c. moving said ultrasound transducer in accordance with said relationships to thereby locate said region of interest of said subject's calcaneus; 
 wherein said moving step includes the substep of adjusting a position of a marker corresponding to said size by a distance, adjustment of said marker causing movement of said ultrasound transducer. 
 
     
     
       14. The method according to  claim 13 , wherein said at least one size includes a length from said back of said foot to a head of a first metatarsal of said foot. 
     
     
       15. The method of  claim 13 , wherein said side of a heel is a medial side. 
     
     
       16. The method of  claim 13 , wherein said side of a heel is a lateral side. 
     
     
       17. A method for positioning an ultrasound transducer at a region of interest of a calcaneus within a foot of a subject, comprising the following steps:
 a. Placing said subject's foot in a fixture such that said ultrasound transducer is disposed on a side of a heel of said foot, said fixture containing a surface upon which a bottom of said foot rests; 
 b. Selecting relationships between x and y motions of said ultrasound transducer, and a reference frame, and identifying at least one size associated with said foot of said subject; 
 c. moving said ultrasound transducer in accordance with said relationships to thereby locate said region of interest of said subject's calcaneus; 
 wherein said moving step includes the substep of adjusting a position of a marker corresponding to said size by a distance, adjustment of said marker causing movement of said ultrasound transducer. 
 
     
     
       18. The method according to  claim 17 , wherein said at least one size includes a length from a back of said foot to a head of a first metatarsal of said foot. 
     
     
       19. The method of  claim 17 , wherein said side of a heel is a medial side. 
     
     
       20. The method of  claim 17 , wherein said side of a heel is a lateral side. 
     
     
       21. Apparatus for positioning at least one ultrasound transducer at a region of interest of a calcaneus within a foot of a subject, said apparatus comprising:
 a fixture comprising at least one surface and further comprising at least one ultrasound transducer, and means for moving said at least one ultrasound transducer according to a set of relationships, wherein said set of relationships includes means for utilizing at least one size associated with the foot of the subject, and wherein said set of relationships also include means for using a reference frame, whereby said region of interest may be located on the calcaneus within the foot of the subject; 
 and a marker positioned on said fixture, 
 wherein said moving means adjusts a position of said marker corresponding to said size by a distance, adjustment of said marker causing movement of said at least one ultrasound transducer. 
 
     
     
       22. Apparatus according to  claim 21 , wherein said at least one size includes a length from a back of the foot to a head of a first metatarsal of the foot. 
     
     
       23. Apparatus according to  claim 21 , wherein said at least one transducer comprises a first transducer and a second transducer configured to be located on a medial and a lateral side of a heel, respectively, of the foot of the subject.